In the background art, there is an air conditioning apparatus which has a refrigerant circuit where expansion valves are provided on the upstream side and the downstream side of a receiver and gas refrigerant is injected from the receiver into a compressor as shown in Japanese Unexamined Patent Application Publication No. H10-132393. In detail, the air conditioning apparatus has the refrigerant circuit which is configured by connecting the compressor, a radiator, an upstream side expansion valve, the receiver, a downstream side expansion valve, and an evaporator. An injection circuit which injects intermediate-pressure gas refrigerant from the receiver into the compressor is provided in the refrigerant circuit. Then, in the air conditioning apparatus, operation where refrigerant is circulated in the order of the compressor, the radiator, the upstream side expansion valve, the receiver, the downstream side expansion valve, and the evaporator is performed and intermediate-pressure gas refrigerant is injected from the receiver into the compressor.
In addition, there is an air conditioning apparatus which uses R32 as refrigerant as shown in Japanese Unexamined Patent Application Publication No, 2001-194015. In detail, the air conditioning apparatus has a refrigerant circuit which is configured by connecting a compressor, a radiator, an expansion valve, and an evaporator. Then, in the air conditioning apparatus, there is suction wetting control where the number of rotations of the compressor and/or the opening of the expansion valve is changed such that refrigerant at the outlet of the evaporator is in a designated wetting state while performing operation where refrigerant is circulated in the order of the compressor, the radiator, the expansion valve, and the evaporator.